Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

Bronze

UDP segment reassembly |NO seq num in UDP header|

Hi everybody

 

I hope you are doing fine. 

 

A quick question for you guys

 

Let say we have two host:

 

A------B

 

A wants to transfer data to B using UDP

 

Assume A  has a UDP segment of 10000  bytes to send to B

A chops down these 10000 bytes into each 1000 bytes chunk and sends total 10 packets to B, each carrying 1000 bytes as IP pay load.

 

B will wait for all the 10 packets, once all received, B ( ip layer) reassembles them into a UDP segment of 10000 bytes and gives it to UDP layer for processing.

 

1) UDP header has no seq number , so how does B determine all these packets belong to  a particular UDP segment ?

 

2) How does B knows that it has received the last packet belonging to a particular UDP segment and it is time to reassemble this last packet and give the reassembled UDP segment to UDP layer?

 

Thanks

 

 

1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Silver

Hello Sarah,IPv4 header

Hello Sarah,

IPv4 header provides in this case the fragmentation and reassembly services, UDP just uses it being the upper layer protocol

last fragment has the M more fragments not set in the IPv4 header

 

Hope to help

Giuseppe

 

 

 

2 REPLIES
Hall of Fame Super Silver

Hello Sarah,IPv4 header

Hello Sarah,

IPv4 header provides in this case the fragmentation and reassembly services, UDP just uses it being the upper layer protocol

last fragment has the M more fragments not set in the IPv4 header

 

Hope to help

Giuseppe

 

 

 

Bronze

Thanks Giuseppe.  

Thanks Giuseppe.

 

 

163
Views
0
Helpful
2
Replies
CreatePlease login to create content